Antivirus Evasion

  Antivirus Evasion

Training on Antivirus Evasion Techniques

Antivirus evasion is a critical skill for cybersecurity professionals, particularly those involved in penetration testing and red teaming.

Overview of Antivirus Detection

Understanding how antivirus software detects threats is crucial. Most AV solutions use a combination of:

• Signature-Based Detection: Identifies known malware by comparing files against a database of signatures.
• Heuristic Analysis: Looks for suspicious behavior or anomalies in code execution.
• Behavioral Detection: Monitors the behavior of programs in real-time to identify malicious activities.

Key Evasion Techniques

1. Obfuscation

• Code Obfuscation: Alters the code structure to make it difficult for AV software to analyze. Techniques include renaming variables and functions and inserting misleading code.
• Dynamic Shellcode Injection: Injects shellcode into legitimate processes, allowing execution without detection.

2. Packing and Encryption

• Packers: Compress and encrypt the malicious payload, changing its binary structure to evade detection.
• Crypters: Encrypt the code, decrypting it only in memory during execution.

3. In-Memory Execution

• Fileless Malware: Operates entirely in memory, avoiding traditional file-based detection methods. This includes techniques like process hollowing and DLL injection.

4. Anti-VM Checks

• Techniques that detect if the malware is running in a virtualized environment, allowing it to alter its behavior accordingly.

Practical Demonstrations

1. Invoke-Obfuscation Tool: A PowerShell tool used to obfuscate scripts to bypass AV detection.
2. Shelter Tool: A framework for dynamic shellcode injection that helps execute payloads without writing them to disk.

Hands-On Exercises

Participants should engage in practical exercises using virtual machines set up for testing:

• Evasion Development Environment: Set up a Windows server with administrative privileges to develop and debug payloads.
• Target Environment: Use a Windows server with low-privileged access to practice evasion techniques against common AV solutions like Microsoft Defender.

Recommended Resources

1. Online Courses:
   • Introduction to Windows Evasion Techniques on HTB Academy focuses on bypassing Microsoft Defender with hands-on labs.
2. GitHub Repositories:
   • Explore repositories like Evasion-Practice for various C# evasion techniques 
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3. Books:
   • Antivirus Bypass Techniques provides insights into practical methods for circumventing AV solutions.
4. Frameworks:
   • Familiarize yourself with the MITRE ATT&CK framework for a comprehensive list of evasion techniques.
   
   

Training on Antivirus Evasion Software: Key Components and Operations

This training module focuses on the essential components and operational techniques of antivirus evasion software. Participants will gain a comprehensive understanding of how these techniques work, their applications, and practical demonstrations.

Understanding Antivirus Detection Mechanisms

Before delving into evasion techniques, it's crucial to understand how antivirus software detects threats:

• Signature-Based Detection: Identifies known malware by comparing files against a database of signatures.
• Heuristic Analysis: Analyzes code characteristics and behaviors to detect potential threats.
• Behavioral Detection: Monitors program behavior in real-time to identify malicious activities.
• Sandboxing: Executes code in a controlled environment to observe its behavior without affecting the host system.

Key Components of Antivirus Evasion Software

1. Obfuscators
   • Function: Disguise harmful code to make it difficult to analyze or reverse engineer.
   • Techniques: Includes renaming variables, inserting dead code, and altering control flows.
2. Packers
   • Function: Compress and encrypt malicious payloads to change their binary structure.
   • Outcome: Creates a new executable that appears benign to AV software while containing the malicious payload.
3. Crypters
   • Function: Encrypts the code and decrypts it at runtime, making detection challenging.
   • Mechanism: The decryption stub is executed in memory, preventing the AV from detecting the malicious code on disk.
4. Droppers and Loaders
   • Dropper: Delivers a malicious payload to the victim's system and may establish persistence.
   • Loader: Loads additional malware into memory, often using process injection techniques to evade detection.
5. Handlers
   • Function: Communicate with command and control (C&C) servers to receive commands for executing malicious activities.

Evasion Techniques

On-Disk Evasion Techniques

These methods modify the malicious code on disk to avoid detection:

• Obfuscation: Reorganizes code to hinder analysis.
• Encoding: Converts data into a different format using algorithms.
• Packing: Compresses code into a new executable format.
• Crypters: Encrypts code, decrypting it only in memory.

In-Memory Execution Techniques

These techniques execute code directly in memory without writing it to disk:

• Fileless Malware: Operates entirely in memory, avoiding traditional file-based detection methods.
• Process Hollowing: Injects malicious code into legitimate processes running on the system.

Practical Demonstrations

1. Invoke-Obfuscation Tool
   • A PowerShell tool used for obfuscating scripts to bypass AV detection.
2. Veil-Evasion Framework
   • A Python-based framework for generating payloads that can evade many antivirus solutions.
3. Using msfvenom
   • Generate a payload using msfvenom and test its detection rate against various AV solutions using VirusTotal.

Hands-On Exercises

Participants will engage in practical exercises:

• Set up a controlled environment with both vulnerable systems and AV solutions for testing evasion techniques.
• Use tools like peCloak and Shellter to automate evasion processes and test effectiveness against different antivirus products.

Training on AV Evasion in Practice

This training module is designed to equip participants with practical knowledge and skills in antivirus evasion techniques. Understanding how to bypass antivirus solutions is crucial for effective penetration testing and red teaming.

Overview of Antivirus Evasion

Antivirus evasion involves using various techniques to prevent detection by antivirus software. This is essential for successfully executing penetration tests, as many organizations rely heavily on AV solutions to protect their systems.

Key Techniques for Antivirus Evasion

1. Obfuscation

• Definition: The process of altering code to make it difficult for antivirus software to analyze or detect.
• Methods:
  • Renaming variables and functions.
  • Inserting dead code or misleading instructions.
  • Using control flow obfuscation to complicate the execution path.

2. Packing

• Definition: Compressing and encrypting the malicious payload to change its binary structure.
• Tools:
  • Veil-Evasion: A framework that generates payloads designed to evade detection by most AVs.
  • Example Command:

    bash
    veil-evasion
    

    Followed by selecting a payload and generating it.

3. Dynamic Shellcode Injection

• Definition: Injecting shellcode into a running process, allowing execution without writing files to disk.
• Tools:
  • Shelter: A tool for dynamic shellcode injection that helps execute payloads in memory.

4. In-Memory Execution

• Definition: Running code directly in memory, avoiding traditional file-based detection methods.
• Techniques:
  • Fileless malware execution, where the payload is delivered and executed entirely in memory.

Practical Demonstrations

1. Using Invoke-Obfuscation
   • A PowerShell tool that can obfuscate scripts to bypass AV detection. Participants will learn how to use it effectively.
2. Setting Up a Lab Environment
   • Create a controlled environment with both vulnerable systems and various antivirus solutions for testing evasion techniques.
3. Hands-On Exercises
   • Participants will practice deploying backdoored executables and monitoring connections using Metasploit's multi-handler.

Advanced Evasion Techniques

• Anti-VM Checks: Techniques that detect when malware is running in a virtualized environment, allowing it to alter its behavior.
• Memory-Zeroing Techniques: Clearing sensitive information from memory after execution to avoid detection by forensic tools.

Resources for Further Learning

1. Online Courses:
   • Mastering Antivirus Evasion Techniques on platforms like Hack The Box Academy provides in-depth training on bypassing AV solutions.
2. Community Forums:
   • Engage with communities like Reddit’s r/Malware for discussions on current evasion techniques and tools.
3. MITRE ATT&CK Framework:
   • Utilize the framework for a comprehensive list of evasion techniques and strategies.
   
   

Training on AV Evasion in Practice: Real-World Examples

This training module focuses on practical antivirus evasion techniques, supplemented by real-world examples of their application in notable cyber incidents. Understanding these techniques and their implications is essential for cybersecurity professionals engaged in penetration testing and red teaming.

Overview of Antivirus Evasion Techniques

Antivirus evasion involves employing various strategies to bypass detection mechanisms used by antivirus software. Key techniques include:

• Obfuscation: Altering code to make it difficult to analyze.
• Packing: Compressing and encrypting malicious payloads.
• In-Memory Execution: Running code directly in memory without writing it to disk.
• Process Injection: Injecting malicious code into legitimate processes.

Real-World Examples of AV Evasion Techniques

1. WIZARD SPIDER and Cobalt Strike

• Incident: In a recent case analyzed by CrowdStrike, the adversary WIZARD SPIDER utilized rundll32.exe to execute malicious code under the guise of legitimate processes. This allowed them to gain remote access after a phishing attack, leading to further exploitation through DLL injection.
• Technique Used: The attackers concealed their operations by leveraging signed processes, making it harder for antivirus solutions to detect their activities. This incident underscores the effectiveness of using legitimate tools for malicious purposes.

2. Use of Certutil for Bypass

• Incident: A China-nexus adversary was discovered using Certutil commands to decode and execute binaries via batch scripts. They also employed DLL search order hijacking to install a PlugX implant.
• Technique Used: By manipulating legitimate Windows commands and processes, the attackers were able to bypass AV detection, demonstrating the effectiveness of combining legitimate tools with malicious intent.

3. Petya Ransomware

• Incident: The Petya ransomware attack in 2016 utilized sophisticated methods to infect systems, including process injection techniques that allowed it to evade detection by traditional AV solutions.
• Technique Used: Petya modified system processes and leveraged the operating system’s own functionality against itself, showcasing how attackers can exploit system vulnerabilities while remaining undetected.

4. Stuxnet Worm

• Incident: The Stuxnet worm, which targeted Iran's nuclear facilities, used multiple zero-day vulnerabilities and was capable of spreading via USB drives. It executed its payload without needing an internet connection.
• Technique Used: Stuxnet’s ability to remain stealthy while executing complex operations illustrates the potential for sophisticated malware to evade detection through innovative delivery methods.

Practical Demonstrations

1. Invoke-Obfuscation Tool
   • Participants will practice using the Invoke-Obfuscation tool to obfuscate PowerShell scripts, making them less detectable by AV solutions.
2. Metasploit Framework
   • Using Metasploit, participants will generate payloads and test their detection rates against various antivirus products. This hands-on exercise will illustrate how packing and encoding techniques can reduce detection rates.
3. Dynamic Shellcode Injection with Shelter
   • Participants will learn how to use Shelter for dynamic shellcode injection, allowing them to execute payloads in memory without writing them to disk.

Advanced Evasion Techniques

• Anti-VM Checks: Techniques that detect virtual environments and alter behavior accordingly.
• Memory-Zeroing Techniques: Clearing sensitive information from memory after execution to avoid forensic analysis.

Real-World Examples of Antivirus Evasion Techniques Used in High-Profile Cyber Attacks

Understanding how cybercriminals evade antivirus detection is crucial for cybersecurity professionals. This section highlights notable real-world incidents where antivirus evasion techniques were effectively employed.

1. WIZARD SPIDER and PlugX Implant

• Incident: WIZARD SPIDER, a threat group linked to Russia, utilized the Certutil command to decode and execute binaries from batch scripts. They also employed DLL search order hijacking to install the PlugX implant, disguising it as a legitimate Windows service.
• Technique Used: By manipulating legitimate Windows tools and processes, they successfully bypassed antivirus detection, demonstrating advanced evasion tactics while maintaining stealth during reconnaissance activities .

2. Stuxnet Worm

• Incident: The Stuxnet worm, which targeted Iran's nuclear facilities, exploited multiple zero-day vulnerabilities and was capable of infecting systems via USB drives. It was designed to manipulate industrial control systems while remaining undetected.
• Technique Used: Stuxnet utilized sophisticated packing and encryption methods to conceal its payload and employed stealth techniques to evade detection by traditional antivirus solutions .

3. Petya Ransomware

• Incident: In 2016, Petya ransomware caused widespread disruption by encrypting entire hard drives rather than individual files. It spread rapidly across networks using a combination of phishing emails and exploitation of SMB vulnerabilities.
• Technique Used: Petya utilized process injection techniques to hide its operations within legitimate system processes, effectively evading detection by antivirus software .

4. LockerGoga Ransomware

• Incident: LockerGoga ransomware impacted several large organizations in 2019, including Altran Technologies and Norsk Hydro. It encrypted files and demanded ransom payments in cryptocurrency.
• Technique Used: The attackers used social engineering tactics to deliver the malware, employing obfuscation and packing techniques to evade detection by antivirus solutions 
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5. Zeus Trojan

• Incident: The Zeus Trojan, first identified in 2007, is notorious for stealing banking credentials through phishing attacks. It has infected numerous high-profile targets, including major financial institutions.
• Technique Used: Zeus utilized code mutation techniques to change its appearance while retaining functionality, making it difficult for antivirus software to detect it .

6. MyDoom Worm

• Incident: MyDoom became one of the fastest-spreading email worms in history in 2004, targeting major technology companies like Google and Microsoft.
• Technique Used: The worm employed email-based social engineering tactics and stealth techniques to hide its presence from antivirus software while executing DDoS attacks .